Slow right down, and practice at a very slow tempo, with a metronome. Speed up very gradually, and only when you can play the exercise perfectly at the slow tempo.

Try to get rid of all tension in your hands, arms and shoulders - the classical guitarists' playing position helps with this.

Practice a lot. Scales, arpeggios, study pieces. Commit to the guitar, and it will yield great results (*Zen Buddhism moment*).
i do 1234 on all strings up to fret 21 every day. True to play fast u gotta know where ur going on the fret board. Dont worry about speed it will come with time.
My newest cover Rivers Of Babylon sublime style.


My gear:
taylor 310
Fender strat MiM
Cry Baby-GCB-95
Tone port ux2
tascam dp4
80s rock, classic rock, classic metal